A liquid crystal display (LCD) is one type of the most popular flat panel displays available in the market. As shown in FIG. 1, for example, a conventional thin film transistor liquid crystal display (TFT-LCD) comprises a backlight unit (BLU) 10, an optical sheet 20, and a liquid crystal display panel 30 assembled with a color filter (CF) substrate and a TFT array substrate disposed sequentially on top of each other. The LCD display can further comprise a mold frame 50 disposed on at least one side of the display including the backlight unit 10, the optical sheet 20, and the panel 30 in order to fix and connect these parts. The LCD can also comprise an outer frame 40 disposed on the outside of the backlight unit 10, the optical sheet 20, the panel 30, and the mold frame 50. The backlight unit 10 can comprise a light guide plate 11, lamps 12 disposed on both sides of the light guide plate 11, a reflective plate 13 enclosing the lamps 12 and the light guide plate 11. The optical sheet 20 can comprise a plurality of optical films such as a diffusing film and a prism film in order to control the light towards the light guide plate. The panel is assembled with the color filter substrate 31 and the array substrate 32 with a liquid crystal layer disposed therebetween. The outer frame 40 is disposed at the periphery to provide support for the whole LCD. The mold frame 50 is fabricated by injection molding in order to fix and connect the parts such as the back light unit 10, the optical sheet 20 and the panel 30. A protrusion is formed on the mold frame 50 in order to maintain a spacing between the panel 30 and the optical sheet 20. The spacing can be about 1.0 mm.
The detailed structure of the panel 30 is shown in FIG. 2. In the panel 30, a black matrix (BM) 311 is disposed on inner side of the color filter substrate 31 for blocking the functional elements on the array substrate 32. Besides TFT switching devices, for example, the pixel electrodes array (ITO) 322, data lines 323 and the blocking bars (S/B) 324 between the data lines 323 and the pixel electrodes 322 are also disposed on the array substrate 32. In the operation of the LCD, the pixel electrodes on the color filter substrate may form a distorted electric field with the pixel electrodes on the array substrate and the data lines, thus forming a gap. In that case, the light from the light guide plate may leak through the gap between the blocking bars 324 and the data lines 323, as shown in FIG. 2. Most of the leaked lights can be blocked by the black matrix 311 disposed on the color filter substrate 31. However, when the panel is bended downwards under an external force as shown in FIG. 3, the black matrix 311 for blocking the lights would be shifted by a distance d2 from a desired position, thus forming a gap between the black matrix 311 and the pixel electrodes 322, as shown in FIG. 4, so that the light leaked through the gap between the blocking bars 324 and the data lines 323 can further leak through the gap between the black matrix 311 and the pixel electrodes 322. The further the panel is bended, the larger the black matrix would be shifted, thus deteriorating the leakage, which causes a touch mura phenomenon on the LCD.
In the conventional LCD as shown in FIG. 1, in order to prevent contact wearing, a gap is typically formed between the array substrate 32 and the optical sheet 20, for example, the gap with the height of d1 shown in FIG. 1. The height of d1 is typically about 1.0 mm due to the limitation of the injection molding. This gap allows the panel 30 to bend more and further deteriorate the light leakage and touch mura phenomenon.
Increasing the area of the black matrix on the color filter substrate can prevent the light leakage even if the black matrix was shifted by a distance due to the bending of the liquid crystal panel, however, in that case, the aperture ratio is decreased and the brightness of the LCD is compromised.